You could get a decent 4 channel AND a mono amp for around the same price.
Audio Control ACM 1.300 and an ACM 4.300 $660
Kicker 47KEY200.4 and a 47KEY500.1 for $475
Kenwood Excelon X302-4 and a Excelon X502-1 $400 or the compact KAC amps
D4S new Mini amps MM1004 - $150
The list goes on...